Color images are customarily obtained in the photographic art by reaction between an oxidation product of a silver halide developing agent and a dye-forming coupler. Pyrazolones are useful for forming magenta dye images; however, such couplers have shortcomings with respect to color reproduction in that the unwanted absorption around 430 nm causes color turbidity. Bicyclic pyrazolo couplers, particularly pyrazolotriazole couplers, represent another class of couplers for this purpose. Examples of pyrazoloazole couplers are described in, for example, U.S. Pat. Nos. 4,443,536, 4,665,015; 4,514, 490; 4,621,046, 4,540,654; 4,590,153; 4,822,730 and European Patents 177, 765 and 119,860. One class of pyrazolotriazole couplers includes 1H-pyrazolo[3,2-c][1,2,4]triazole couplers and another includes 1H-pyrazolo[1,5-b][1,2,4]triazole couplers, such as described in European Patent 177,765. While these couplers have adequate reactivity towards oxidized developer to provide an image, it is desirable to have higher activity than currently available. The increase in activity enables less coupler, silver, coupler solvent, and gelatin to be coated and can result in a thinner magenta layer. Thinner layers allow decreased processing time and improved developability of the film.
Occasionally, the developer solution can become back-contaminated with various quantities of the bleach-fix solution. At low contaminate concentrations (<0.2 mL/L), sensitometric changes are minimal but at higher contamination levels, substantial sensitometric changes can occur. Sensitometric changes associated with such gross bleach-fix contamination include speed and contrast shifts (positive or negative) and losses in maximum density (Dmax). The magnitude of these response changes is highly dependent on coupler structure. It is therefore desirable to provide 1H-pyrazolo[1,5-b][1,2,4]triazole couplers that exhibit very low sensitivities to bleach-fix contamination of the developer solution and high photographic activity.